Brake rotors and clutches have been the subject of a variety of patents. The engagement surfaces of a brake rotor and clutch have typically been made of an iron-bearing metal, such as cast iron, steel or stainless steel. Many patents have been related to specific rotor or clutch designs, geared toward elimination of galling and build up of material on the engagement surfaces.
Recently, McMurray in U.S. Pat. No. 4,756,392 described a stainless steel rotor having depressions on the braking surface which act to minimize galling.
Although much work has been done in the area of brake rotors and clutches, new lightweight metallic composites have not made inroads in this area. In fact, the nature of the material has lead those skilled in the art away from using such composites for this application, due to the abrasiveness of the material. Historically, abrasive materials did not make desirable friction surfaces.